1. Field of the Invention
This invention relates to apparatus for cleaning sewer lines, pipe lines, and closed chambers and/or conduits in which water is jetted into the conduits at high pressures and in which a partial vacuum is applied for removal of liquids and solids from the conduits.
2. Description of the Prior Art
It is well-known to provide a mobile sewer cleaning unit having a reservoir for a large supply of water, and water-handling components including a hose reel, a hose normally coiled thereon, and a high pressure pump suitably connected between the reservoir and the hose to deliver water to the hose at high pressure. A nozzle which is typically attached to the free end of the hose reverses the direction of the high-pressure water in such a way as to develop a reaction force which pulls the hose into the sewer line from the hose reel. It is also conventional practice to provide a drive means for the pump including an internal combustion engine, the water handling components and drive means usually being mounted upon a rear platform of a truck or on the bed of a trailer.
It is also well-known to provide such sewer cleaning units with means for collecting the debris flushed from the sewer line by the high-pressure water system. Such debris collecting means typically include a receptacle for storing debris, a boom-mounted conduit extending from the receptacle, an intake tube at the end of the conduit to be lowered into the sewer or other chamber from which the debris is removed, and means for creating a suction force at the intake tube to suck the debris through the conduit and into the receptacle.
The suction creating means used in sewer cleaning units are generally either air conveyance systems or vacuum systems. Air conveyance systems for pickking up debris from sewer pipes and similar chambers are well-known, such as that shown in U.S. Pat. No. 3,568,589, issued to R. E. Shaddock. Such units use a large fan or compressor to create an air flow in the conduit which carries debris to a receiving tank. In contrast to these air conveyance systems, vacuum systems utilize a vacuum pump to create a partial vacuum in a collecting tank. With this vacuum, solid and liquid material in the sewer pipe or chamber is sucked through the conduit into the tank.
In general, sewer cleaning units using vacuum systems have advantages over those using air conveyance systems. Air conveyance units use an open exhaust system for their fan or compressor. When the debris tank is over-filled, contaminated water is picked up into the air stream and discharged into the atmosphere, polluting the air and damaging any objects which are sprayed. In contrast, vacuum units use a completely sealed system. When the tank becomes completely full, an automatic check valve system may be used to shut off the vacuum pump to prevent discharge of the contaminanted material.
Furthermore, vacuum units by reason of the high suction created in the tank are capable of collecting both liquid and solid material. The air movement created by an air conveyance system is capable of drawing with it solid particulate debris, but it is limited in drawing up large amounts of liquid. If water in the sewer covers the intake tube on an air conveyance unit, it will cut down the suction capability of the unit. On the other hand, vacuum systems are especially adapted to pick up liquids, since the end of the intake should be sealed in order to maintain a vacuum in the system, and this seal is usually accomplished by submerging the end of the intake tube below the water line in the sewer chamber.
In prior sewer cleaning units, the water storage reservoir tank and the debris receiving tank were either constructed in two separate tanks or in a single tank having a vertical separation. The construction of two separate tanks is costly, and the use of a single vertically divided tank creates numerous problems. The vertically separated tanks permit connection of the suction conduit only at the rear of the tank. If the debris were to be stored in the front of the tank, it would be necessary to reposition the vertical divider so that the debris could be dumped out through the rear compartment. This design is unacceptable because all of the water in the rear of the tank is then lost or dumped out with the debris.
The connection of the conduit at the rear of the tank presents various problems such as axle overloads on the vehicle. When the conduit and its supporting boom is mounted at the rear of the vehicle, there are increased loads on the rear of the vehicle, requiring an increased number of rear axles. The connection of the conduit at the rear of the vehicle also requires the operator to stand at rear of vehicle while operating the unit, thus exposing the operator to the hazards of oncoming traffic when operating the unit on busy city streets. While it would be desirable for the operator to stand in front of the vehicle and to be protected by the vehicle while operating the unit, this would require extending the rear-mounted conduit to the front of the vehicle, resulting in an extremely long conduit which would decrease the vacuum and suction capability at the intake end of the conduit.